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The translocation of mitochondrial preproteins coded in the nucleus to the mitochondria is mediated by the preprotein translocase of the outer membrane of mitochondria or TOM complex. The Neuroepora TOM complex was purified and analyzed to determine its composition and functional properties. The complex measures 138 angstrom units and contains two to three pores with a diameter of 20 angstrom units.

Spectral studies of the main chlorophyll a/b binding protein from chloroplast membranes indicate that monomerization of the protein results in the disappearance of a few bands. The excitonic coupling of similar pigments in different monomers during trimerization results in the absence of these bands. Further analysis of the spectrum indicates that phosphatidylglycerol plays an important part in the structure of monomers.

H+-coupled transporter of peptide-derived antibiotics and oligopeptides from the small intestine of rabbits are cloned to determine their functional characteristics. The active movement of organic solutes in the plasma membrane is driven by the sodium ion gradient in mammals. The protein pepT1 has a broad substrate specificity and the uptake of the protein is electrogenic, which is not influenced by the membrane potential.

Abstract Background Poly(3-hydroxybutyrate) (PHB) granules are important storage compounds of carbon and energy in many prokaryotes which allow survival of the cells in the absence of suitable carbon sources. Formation and subcellular localization of PHB granules was previously assumed to occur randomly in the cytoplasm of PHB accumulating bacteria. However, contradictionary results on subcellular localization of PHB granules in Ralstonia eutropha were published, recently. Results Here, we provide evidence by transmission electron microscopy that PHB granules are localized in close contact to the nucleoid region in R. eutropha during growth on nutrient broth. Binding of PHB granules to the nucleoid is mediated by PhaM, a PHB granule associated protein with phasin-like properties that is also able to bind to DNA and to phasin PhaP5. Over-expression of PhaM resulted in formation of many small PHB granules that were always attached to the nucleoid region. In contrast, PHB granules of ∆phaM strains became very large and distribution of granules to daughter cells was impaired. Association of PHB granules to the nucleoid region was prevented by over-expression of PhaP5 and clusters of several PHB granules were mainly localized near the cell poles. Conclusion Subcellular localization of PHB granules is controlled in R. eutropha and depends on the presence and concentrations of at least two PHB granule associated proteins, PhaM and PhaP5.

Protein stability is a key factor in successful structural and biochemical research. However, the approaches for systematic comparison of protein stability are limited by sample consumption or compatibility with sample buffer components. Here we describe how miniaturized measurement of intrinsic tryptophan fluorescence (NanoDSF assay) in combination with a simplified description of protein unfolding can be used to interrogate the stability of a protein sample. We demonstrate that improved protein stability measures, such as apparent Gibbs free energy of unfolding, rather than melting temperature Tm, should be used to rank the results of thermostability screens. The assay is compatible with protein samples of any composition, including protein complexes and membrane proteins. Our data analysis software, MoltenProt, provides an easy and robust way to perform characterization of multiple samples. Potential applications of MoltenProt and NanoDSF include buffer and construct optimization for X‐ray crystallography and cryo‐electron microscopy, screening for small‐molecule binding partners and comparison of effects of point mutations. [ABSTRACT FROM AUTHOR]